SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '383df1a65a7395627edbb5336c2c78f4cf92add09e09a7b2f06fe7b14ced3fa3' 
  AND token = '3k5dU4+XWS97b8NjFjstCOgHwUibUxJojpSGQymCQBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}